Fastening elements of this general type are not known in the lamp field.
Similar fastening elements, however, are used in the automotive industry and are designated as expansion rivets. A similar fastening element is known from example from WO 2005/071273 A1 relating to different art. This expansion rivet is typically used in the automotive industry to fixate interior fairing elements at a vehicle body.
In the lamp industry LEDs are increasingly used as illuminants. LEDs are typically arranged on a circuit board which typically provides good heat dissipation. Conductive paths are arranged on a top side of the circuit board in order to electrically connect the LEDs. These conductive paths have to be offset relative to metal elements or they have to be insulated. These circuit boards are attached on a reactive bearing which is configured for example as a cooling element and which represents a lamp element or forms a portion of a lamp housing. During assembly of the circuit board on the lamp element selecting a correct contact pressure is very important since the contact pressure is a significant factor for quality of the heat dissipation from the LED to the lamp element.
A fastening element which fixates individual circuit boards provided with LEDs on a lamp element is known for example from DE 10 2008 005 823 A1. Thus, an annular connecting element is placed onto the circuit board and supports the circuit board between itself and a reaction bearing, for example a cooling element. The connecting element is connected with the reaction bearing through bolts. The tightening torque of the bolts defines the contact pressure between the circuit board and the reaction bearing.
Increasing mass production of LED lamps of various types requires fastening elements for the circuit boards provided with LEDs which fastening elements are configured for automated manufacturing methods. Thus, fastening elements of this type have to satisfy stringent requirements with respect to permanently supporting the circuit board and permanently maintaining the contact pressure. These requirements are due to a projected service life of the LED illuminant of up to 50,000 hours.
Thus, it is an object of the invention to provide a fastening element which is configured for an automated fabrication of lamps and which provides a defined contact pressure between the LED and the lamp element.